Techniques to compensate for movement of sensors in a vehicle

ABSTRACT

Techniques are described for compensating for movements of sensors. A method includes receiving two sets of sensor data from two sets of sensors, where a first set of sensors are located on a roof of a cab of a semi-trailer truck and a second set of sensor data are located on a hood of the semi-trailer truck. The method also receives from a height sensor a measured value indicative of a height of the rear of a rear portion of the cab of the semi-trailer truck relative to a chassis of the semi-trailer truck, determines two correction values, one for each of the two sets of sensor data, and compensates for the movement of the two sets of sensors by generating two sets of compensated sensor data. The two sets of compensated sensor data are generated by adjusting the two sets of sensor data based on the two correction values.

CROSS-REFERENCES TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 17/025,257 titled “TECHNIQUES TO COMPENSATE FOR MOVEMENT OFSENSORS IN A VEHICLE,” filed Sep. 18, 2020, which is a continuation ofU.S. patent application Ser. No. 16/565,331 titled “TECHNIQUES TOCOMPENSATE FOR MOVEMENT OF SENSORS IN A VEHICLE,” filed on Sep. 9, 2019,now U.S. Pat. No. 10,798,303. The disclosures of the above-mentionedpatent documents are hereby incorporated by reference in its entirety.

TECHNICAL FIELD

This document relates to systems, apparatus, and methods to compensatefor sensor misalignment due to a vehicle's movements.

BACKGROUND

Autonomous vehicle navigation is a technology that can allow a vehicleto sense the position and movement of vehicles around an autonomousvehicle and, based on the sensing, control the autonomous vehicle tosafely navigate towards a destination. A vehicle can operateautonomously based on data obtained from multiple sensors located on thevehicle. An autonomous vehicle may operate in several modes. In somecases, an autonomous vehicle may allow a driver to operate theautonomous vehicle as a conventional vehicle by controlling thesteering, throttle, clutch, gear shifter, and/or other devices. In othercases, a driver may engage the autonomous vehicle navigation technologyto allow the vehicle to be driven by itself.

SUMMARY

When a vehicle is driven, sensors mounted on a roof area of the vehiclemay move different from sensors mounted on a hood of the vehicle. Forexample, in a semi-trailer truck, cameras mounted on top of a cab areamay move different from the LiDAR sensors mounted on the hood of thesemi-trailer truck. This patent document describes apparatus and methodsto measure a height of a semi-trailer truck's cab relative to a chassisto which the cab is coupled via an air suspension system. Based on themeasured height, the apparatus and methods can apply a first correctionvalue to sensor data obtained by a first set of sensors located on aroof of the cab and a second correction value to sensor data obtained bya second set of sensors located on a hood of the semi-trailer truck.

An exemplary compensation method, comprises receiving, from a first setsensors, a first set of sensor data of an area towards which asemi-trailer truck is being driven, where the first set of sensors arelocated on a roof of a cab of a semi-trailer truck; receiving, from asecond set sensors, a second set of sensor data of the area, where thesecond set of sensors are located on a hood of the semi-trailer truck;receiving, from a height sensor, a measured value indicative of a heightof a rear portion of a cab of a semi-trailer truck relative to a chassisof the semi-trailer truck, where the height sensor is located at therear portion of the cab; determining, based on the measured value, afirst correction value for the first set of sensor data and a secondcorrection value for the second set of sensor data; and compensating formovements of the first set of sensors and the second set of sensors bygenerating a first set of compensated sensor data and a second set ofthe compensated sensor data, where the first set of compensated sensordata is generated by adjusting the first set of sensor data based on thefirst correction value and where the second set of compensated sensordata is generated by adjusting the second set of sensor data based onthe second correction value.

In some embodiments, the height sensor is located adjacent to airsprings that are coupled to the rear portion of the cab of thesemi-trailer truck. In some embodiments, the first set of sensors andthe second set of sensors move in opposite directions in response toreceiving a physical stimulus. In some embodiments, the first set ofsensors to move upward relative to a plane formed by a chassis of thesemi-trailer truck and the second set of sensors to move downwardrelative to the plane formed by the chassis, and the first set ofsensors to move downward relative to the plane formed by the chassis andthe second set of sensors to move upward relative to the plane formed bythe chassis.

In some embodiments, the first correction value includes a first symbolto indicate that first set of sensors moved upward relative to the planeformed by the chassis and the second correction value includes a secondsymbol to indicate that the second set of sensors moved downwardrelative to the plane formed by the chassis, the first correction valueincludes the second symbol to indicate that the first set of sensorsmoved downward relative to the plane and the second correction valueincludes the first symbol to indicate that the second set of sensorsmoved upward relative to the plane formed by the chassis, and the firstsymbol is different from the second symbol.

In some embodiments, the height sensor includes an ultrasonic distancesensor, a laser distance sensor, a linear potentiometer, or a rotarypotentiometer. In some embodiments, the first correction value and thesecond correction value are determined based on an equation or apre-determined table. In some embodiments, the first set of sensorsinclude a plurality of cameras and the first set of sensor data includescamera images, and the second set of sensors include a plurality oflight detection ranging (LiDAR) sensors and the second set of sensordata includes LiDAR data.

In yet another exemplary aspect, the above-described method is embodiedin a non-transitory computer readable program stored on a non-transitorycomputer readable media. The computer readable program includes codethat when executed by a processor, causes the processor to perform themethods described in this patent document.

In yet another exemplary embodiment, a device that is configured oroperable to perform the above-described methods is disclosed.

In yet another exemplary embodiment, a system for compensating formovement of sensors includes a computer that includes a processorconfigured to perform the above described methods is disclosed.

The above and other aspects and their implementations are described ingreater detail in the drawings, the descriptions, and the claims.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 shows a side view of a semi-trailer truck in a scenario where theair suspension system decompresses.

FIG. 2 shows a block diagram of an example vehicle ecosystem in whichcorrection values for sensors can be determined based on a measuredheight of a semi-trailer truck's cab relative to a chassis of thesemi-trailer truck.

FIG. 3 shows a flow diagram to determine and use two correction valuesfor two sets of sensors located on a vehicle.

DETAILED DESCRIPTION

Developments in autonomous driving technology have led to a developmentof semi-trailer truck that can be autonomously driven to deliver goodsto a destination. A semi-trailer truck is a vehicle that can include atractor unit where a driver sits in a cab and a trailer unit coupled tothe tractor unit. The trailer unit may include goods that thesemi-trailer truck delivers to a destination. When a semi-trailer trucksis driven in an autonomous mode, the semi-trailer truck can operatewithout much intervention from a human driver.

A computer located in the semi-trailer truck can operate thesemi-trailer truck in an autonomous mode by controlling various systemof the semi-trailer truck. For example, the computer can perform imageprocessing on images obtained from cameras on the semi-trailer truck todetermine the location of objects that surround the semi-trailer truck.Based on the image processing, the computer can safely operate thesemi-trailer truck by controlling a steering angle of the steeringsystem, a throttle amount to control the speed of the vehicle, atransmission gear, and/or a braking amount to control the extent towhich the brakes are engaged.

To safely operate the semi-trailer truck in an autonomous mode, severalsensors are distributed around the semi-trailer truck so that thesensors are coupled to different places on the semi-trailer truck. Forexample, a plurality of cameras is coupled to a roof of a cab of thesemi-trailer truck (shown as 104 in FIG. 2) and a plurality of sensors(e.g., LiDARs) are coupled to the hood of the semi-trailer truck (shownas 106 in FIG. 2). Sensors located at different places on thesemi-trailer truck enable a computer located in the semi-trailer truckto obtain sensor data that describes different regions (e.g., front,rear, side) of an environment in which the semi-trailer truck is beingdriven. However, as further explained in FIG. 1, at least one technicalproblem created by the distribution of sensors is that one sensorlocated on a roof of a cab can move differently compared to anothersensor located on a hood when the semi-trailer truck is driven. Sincethe driving operations of the semi-trailer truck is dependent at leastin part on the signal processing of the data obtained by the sensors,the computer can employ compensation techniques to the sensor data tocompensate for the movements of the sensors located on the cab and hoodof the semi-trailer truck.

FIG. 1 shows a side view of a semi-trailer truck 100 in a scenario wherethe air suspension system decompresses. A semi-trailer truck 100includes a cab 102 where a driver can sit or rest. The cab 102 includesa roof to which a plurality of cameras 104 can be mounted. Forsimplicity, a single camera 104 is shown in FIG. 1. The semi-trailertruck 100 also includes a plurality of LiDAR sensors 106 that can becoupled to the hood 101. In some embodiments, one LiDAR sensor can belocated on the driver side of the hood, which is the side shown in FIG.2, and another LiDAR can be located on the passenger side of the hood.

A front portion of the hood 101 is attached with a pivoting mount 108 toa chassis 116 of the semi-trailer truck. A rear portion of the hood 101is coupled to a front region of the cab 102. For example, a latch cancouple the rear portion of the hood 101 to the front region of the cab102 near the door 118. The front of the cab 102 is attached with apivoting mount 110 to the chassis 116. The rear of the cab 102 issuspended on or coupled to air springs of a suspension system 112. Thesuspension system 112 include air springs that can dampen the effect ofvibrations as the semi-trailer truck 100 is driven on a road.

The result of this mounting strategy is that when the air springs in theair suspension system 112 decompress (e.g., when the semi-trailer truckgoes through a pothole), the cab 102 pitches forward while the hood 101pitches rearward as shown with the directional arrows on top of thepivoting mounts 108, 110. When the cab 102 pitches forward and the hood101 pitches rearward, the position of the plurality of camera 104 maychange by an angle relative to the horizon (shown as θ₂ in FIG. 1) andthe position of the LiDAR sensors 106 may change by another anglerelative to the horizon (shown as θ₁ in FIG. 1). Thus, the decompressedair springs can cause at least the plurality of cameras 104 to pitchdownwards relative to an imaginary plane formed by the chassis 116 (ormore counter-clockwise relative to pivoting mount 110) and the LiDARsensors 106 to pitch upwards relative to the imaginary plane formed bythe chassis 116 (or move clockwise relative to pivoting mount 108). Whenthe air springs compress (e.g., when the truck hits a bump), the cab 102pitches rearward while the hood 101 pitches forward. Thus, thecompressed air springs can cause at least the plurality of cameras 104to pitch upwards relative to the imaginary plane formed by the chassis116 and the LiDAR sensors 106 to pitch downwards relative to theimaginary plane formed by the chassis 116.

The result of the movements of the hood 101 and the cab 102 is that thepositions of the sensors mounted to the hood 101 and cab 102 can bebecome misaligned relative to each other or even compared to theposition of the sensors when the semi-trailer truck 100 does notexperience much vibrations (e.g., when the semi-trailer truck is parkedor stopped). In some embodiments, cameras and/or other sensors arecalibrated when the truck is turned on and is in a parked state. Thus,in such embodiments, calibration is performed when the positions of thecameras do not move much. However, when the semi-trailer truck isdriven, the hood 101 and cab 102 tend to move or pivot in a directionopposite to each other, which changes the position of the sensors. Whena computer located in the semi-trailer truck 100 performs signalprocessing on data obtained by the sensors that have moved when the airsprings have compressed, the computer may determine that an object(e.g., another vehicle) in front of the semi-trailer truck 100 is closerthan it is. In this scenario, the computer may instruct the semi-trailertruck 100 to engage its brakes unnecessarily.

To correct the effect of sensor position misalignment, a height sensor114 can be located adjacent to the air suspension system 112 (e.g.,adjacent to the air springs) to measure the height of the rear of thecab 102 relative to the chassis 116. For example, the height sensor 114can be located at or near the rear of the cab 102 to provide maximummeasurement resolution while measuring the height of the rear of the cab102 relative to the chassis 116. Given the mounting of the hood and thecab to the chassis and to each other, a single height sensor 114 can beused to measure the height of the rear of the cab 102 relative to thechassis 116, where a computer can use the measured height to determinecorrection values for both the LiDAR sensors 106 coupled to the hood 101and the plurality of cameras 104 coupled to the cab 102. The heightsensor 114 may be an ultrasonic distance sensor, a laser distancesensor, a linear potentiometer, or a rotary potentiometer.

As further described in FIGS. 2 and 3, based on the measured heightvalue, the obtained correction values can be used to process the sensordata obtained by the plurality of cameras 104 and the LiDAR sensors 106.Thus, the correction values can be used to compensate for themisalignment between sensors in real-time.

FIG. 2 shows a block diagram of an example vehicle ecosystem 200 inwhich correction values for sensors can be determined based on ameasured height of a semi-trailer truck's cab relative to a chassis ofthe semi-trailer truck. An in-vehicle control computer 250 is located inthe semi-trailer truck 205 and can be in data communication with aplurality of vehicle subsystems 240, all of which can be resident in thesemi-trailer truck 205. A vehicle subsystem interface 260 is provided tofacilitate data communication between the in-vehicle control computer250 and the plurality of vehicle subsystems 240.

The semi-trailer truck 205 may include various vehicle subsystems thatsupport of the operation of semi-trailer truck 205. The vehiclesubsystems may include a vehicle drive subsystem 242, a vehicle sensorsubsystem 244, and/or a vehicle control subsystem 246. The components ordevices of the vehicle drive subsystem 242, the vehicle sensor subsystem244, and the vehicle control subsystem 246 as shown as examples. In someembodiment, additional components or devices can be added to the varioussubsystems or one or more components or devices (e.g., Radar shown inFIG. 2) can be removed without affecting the sensor misalignmentcompensation techniques described in this patent document. The vehicledrive subsystem 242 may include components operable to provide poweredmotion for the semi-trailer truck 205. In an example embodiment, thevehicle drive subsystem 242 may include an engine or motor,wheels/tires, a transmission, an electrical subsystem, and a powersource.

The vehicle sensor subsystem 244 may include a number of sensorsconfigured to sense information about an environment or condition of thesemi-trailer truck 205. The vehicle sensor subsystem 244 includes aheight sensor that can measure a height of the rear of the cab relativeto the semi-trailer truck's chassis.

In FIG. 2, the vehicle subsystem interface 260 of the in-vehicle controlcomputer 250 can include a wireless receiver and/or a CAN controllerthat can receive signals transmitted or sent by the height sensor andsend the measured height value in the received signal to the sensorcompensation module 265 for further processing. The sensor compensationmodule 265 receives from the height sensor a measured height value thatindicate a position of the cab relative to a position of the chassis.

The sensor compensation module 265 can use a pre-determined table (asshown in Table 1 below) or an equation to determine a first correctionvalue for a first set of sensors (e.g., cameras) located on the roof ofthe cab of the semi-trailer truck 205 and a second correction value fora second set of sensors (e.g., LiDAR sensors) located on the hood of thesemi-trailer truck 205 based on the measured height value. For example,as shown in Table 1, the sensor compensation module 265 can determine achange in the cab height (A Cab Height) by subtracting the measuredheight value from a pre-determined height of a cab when the cab is in arest position and not subjected to any movements. Based on the measuredheight value, the sensor compensation module 265 can determine the firstcorrection value for the first set of sensors to be a value from the ACab Angle column corresponding to a value from the A Cab Height column;and the sensor compensation module 265 can determine the secondcorrection value for the second set of sensors to be a value from the ALiDAR Angle column corresponding to a value from the A Cab Heightcolumn.

TABLE 1 Pre-Determined Correction Values for Sensors Δ Cab Δ Cab Δ LiDARRelative Height Angle Angle Angle 2.188 1.20 −0.20 1.40 1.688 1.00 −0.201.20 1.438 0.70 −0.10 0.80 1.063 0.50 0.00 0.50 0.813 0.50 0.00 0.500.563 0.40 0.00 0.40 0.313 0.20 0.00 0.20 0.000 0.00 0.00 0.00 −0.0630.00 0.10 −0.10 −0.313 0.00 0.10 −0.10 −0.688 −0.40 0.20 −0.60 −0.938−0.50 0.20 −0.70 −1.313 −0.50 0.30 −0.80In some embodiments, an exemplary equation can be C=(0.638*H), where Cis the correction factor (in degrees), and H is the measured cab height(in inches).

In some embodiments, the first and second correction values can includea symbol (e.g., “+” or “−” indicators) to indicate whether the sensorshave moved upward or downward relative to an imaginary plane formed bythe chassis of the semi-trailer truck. For example, if the cameraslocated on the roof of the cab moved upward relative to the plane formedby the chassis, then the first correction value includes a first symbol(e.g., “+”) to indicate that the cameras moved upward, and if the LiDARsensors move downward relative to the plane formed by the chassis, thenthe second correction value includes a second symbol (e.g., “−”) toindicate that the second set of sensors moved downward. The first symbolcan be different from the second symbol because the cameras on the roofof the cab and LiDAR sensors on the hood tend to move in oppositedirections. Continuing with the above example, if the cameras located onthe roof of the cab moved downward relative to the plane formed by thechassis, then the first correction value includes the second symbol(e.g., “−”) to indicate that the cameras moved downward, and if theLiDAR sensors move upward relative to the plane formed by the chassis,then the second correction value includes the first symbol (e.g., “+”)to indicate that the second set of sensors moved upward.

The first and second correction values can be used by the sensorcompensation module 265 to adjust or shift the images taken by thecameras to obtain compensated image data and to adjust or shift the datafrom the point cloud measured and/or created by the LiDAR sensors toobtain compensated point cloud data. For example, referring to Table 1above, if sensor compensation module 265 determines that the A CabHeight is 1.438, then the sensor compensation module 265 can perform anangular shift or vertical shift or horizontal shift by shifting theimages obtained by the cameras by −0.70 and by shifting the point cloudobtained by the LiDAR sensors by +0.10 to compensate for the change inthe angles of the sensors. This shift can bring both datasets intoalignment to create a more accurate map of the vehicle's surroundings.In some embodiments, the sensor compensation module 265 can perform theangular shift on the point cloud data or the pixels of an image.

Returning to the vehicle sensor subsystem 244, in some embodiments thevehicle sensor subsystem 244 may also include an inertial measurementunit (IMU), a Global Positioning System (GPS) transceiver, a RADAR unit,a laser range finder/LiDAR unit, and/or cameras or image capturedevices. The vehicle sensor subsystem 244 may also include sensorsconfigured to monitor internal systems of the semi-trailer truck 205(e.g., an O₂ monitor, a fuel gauge, an engine oil temperature).

The IMU may include any combination of sensors (e.g., accelerometers andgyroscopes) configured to sense position and orientation changes of thesemi-trailer truck 205 based on inertial acceleration. The GPStransceiver may be any sensor configured to estimate a geographiclocation of the semi-trailer truck 205. For this purpose, the GPStransceiver may include a receiver/transmitter operable to provideinformation regarding the position of the semi-trailer truck 205 withrespect to the Earth. The RADAR unit may represent a system thatutilizes radio signals to sense objects within the local environment ofthe semi-trailer truck 205. In some embodiments, in addition to sensingthe objects, the RADAR unit may additionally be configured to sense thespeed and the heading of the objects proximate to the semi-trailer truck205. The laser range finder or LiDAR unit may be any sensor configuredto sense objects in the environment in which the semi-trailer truck 205is located using lasers. The cameras may include devices configured tocapture a plurality of images of the environment of the semi-trailertruck 205. The cameras may be still image cameras or motion videocameras.

Many or all of the functions of the semi-trailer truck 205 can becontrolled by the in-vehicle control computer 250. The in-vehiclecontrol computer 250 may include at least one data processor 270 (whichcan include at least one microprocessor) that executes processinginstructions stored in a non-transitory computer readable medium, suchas the data storage device 275 or memory. The in-vehicle controlcomputer 250 may also represent a plurality of computing devices thatmay serve to control individual components or subsystems of thesemi-trailer truck 205 in a distributed fashion. In some embodiments,the data storage device 275 may contain processing instructions (e.g.,program logic) executable by the data processor 270 to perform variousmethods and/or functions of the semi-trailer truck 205, including thosedescribed for the sensor compensation module 265 as explained in thispatent document. For instance, the data processor 270 executes theoperations associated with sensor compensation module 265 fordetermining the correction values based on a measured height of the rearof the cab relative to the chassis, and for using the correction valuesto compensate the sensor data obtained from misaligned sensors.

The data storage device 275 may contain additional instructions as well,including instructions to transmit data to, receive data from, interactwith, or control one or more of the vehicle drive subsystem 242, thevehicle sensor subsystem 244, and the vehicle control subsystem 246. Thein-vehicle control computer 250 can be configured to include a dataprocessor 270 and a data storage device 275. The in-vehicle controlcomputer 250 may control the function of the semi-trailer truck 205based on inputs received from various vehicle subsystems (e.g., thevehicle drive subsystem 242, the vehicle sensor subsystem 244, and thevehicle control subsystem 246).

FIG. 3 shows a flow diagram to determine and use two correction valuesfor two sets of sensors located on a vehicle. At the receiving operation302, an in-vehicle control computer receives, from a first set sensors,a first set of sensor data of an area towards which a semi-trailer truckis being driven. The first set of sensors can be located on a roof of acab of a semi-trailer truck. At the receiving operation 304, thein-vehicle control computer receives, from a second set sensors, asecond set of sensor data of the area. The second set of sensors can belocated on a hood of the semi-trailer truck. In some embodiments, thefirst set of sensors include a plurality of cameras and the first set ofsensor data includes camera images, and the second set of sensorsinclude a plurality of light detection ranging (LiDAR) sensors and thesecond set of sensor data includes LiDAR data.

At the receiving operation 306, the in-vehicle control computerreceives, from a height sensor, a measured value indicative of a heightof a rear portion of a cab of a semi-trailer truck relative to a chassisof the semi-trailer truck. The height sensor may be located at the rearportion of the cab. In some embodiments, the height sensor is locatedadjacent to air springs that are coupled to the rear portion of the cabof the semi-trailer truck. In some embodiments, the height sensorincludes an ultrasonic distance sensor, a laser distance sensor, alinear potentiometer, or a rotary potentiometer.

At the determining operation 308, the in-vehicle control computerdetermines, based on the measured value, a first correction value forthe first set of sensor data and a second correction value for thesecond set of sensor data. In some embodiments, the first correctionvalue and the second correction value are determined based on anequation or a pre-determined table.

At the compensating operation 310, the in-vehicle control computercompensates for movements of the first set of sensors and the second setof sensors by generating a first set of compensated sensor data and asecond set of the compensated sensor data. The first set of compensatedsensor data is generated by adjusting (e.g., shifting) the first set ofsensor data based on the first correction value and the second set ofcompensated sensor data is generated by adjusting (e.g., shifting) thesecond set of sensor data based on the second correction value.

In some embodiments, the first set of sensors and the second set ofsensors move in opposite directions in response to receiving a physicalstimulus (e.g., compression or decompression of the air springs or of acomponent of the suspension system). In some embodiments, the first setof sensors to move upward relative to a plane formed by a chassis of thesemi-trailer truck and the second set of sensors to move downwardrelative to the plane formed by the chassis, and the first set ofsensors to move downward relative to the plane formed by the chassis andthe second set of sensors to move upward relative to the plane formed bythe chassis.

In some embodiments, the first correction value includes a first symbolto indicate that first set of sensors moved upward relative to the planeformed by the chassis and the second correction value includes a secondsymbol to indicate that the second set of sensors moved downwardrelative to the plane formed by the chassis, the first correction valueincludes the second symbol to indicate that the first set of sensorsmoved downward relative to the plane and the second correction valueincludes the first symbol to indicate that the second set of sensorsmoved upward relative to the plane formed by the chassis, and the firstsymbol is different from the second symbol. The operations described inFIG. 3 can be performed by a sensor compensation module 265 of anin-vehicle control computer as described in FIG. 2.

In this document the term “exemplary” is used to mean “an example of”and, unless otherwise stated, does not imply an ideal or a preferredembodiment.

Some of the embodiments described herein are described in the generalcontext of methods or processes, which may be implemented in oneembodiment by a computer program product, embodied in acomputer-readable medium, including computer-executable instructions,such as program code, executed by computers in networked environments. Acomputer-readable medium may include removable and non-removable storagedevices including, but not limited to, Read Only Memory (ROM), RandomAccess Memory (RAM), compact discs (CDs), digital versatile discs (DVD),etc. Therefore, the computer-readable media can include a non-transitorystorage media. Generally, program modules may include routines,programs, objects, components, data structures, etc. that performparticular tasks or implement particular abstract data types. Computer-or processor-executable instructions, associated data structures, andprogram modules represent examples of program code for executing stepsof the methods disclosed herein. The particular sequence of suchexecutable instructions or associated data structures representsexamples of corresponding acts for implementing the functions describedin such steps or processes.

Some of the disclosed embodiments can be implemented as devices ormodules using hardware circuits, software, or combinations thereof. Forexample, a hardware circuit implementation can include discrete analogand/or digital components that are, for example, integrated as part of aprinted circuit board. Alternatively, or additionally, the disclosedcomponents or modules can be implemented as an Application SpecificIntegrated Circuit (ASIC) and/or as a Field Programmable Gate Array(FPGA) device. Some implementations may additionally or alternativelyinclude a digital signal processor (DSP) that is a specializedmicroprocessor with an architecture optimized for the operational needsof digital signal processing associated with the disclosedfunctionalities of this application. Similarly, the various componentsor sub-components within each module may be implemented in software,hardware or firmware. The connectivity between the modules and/orcomponents within the modules may be provided using any one of theconnectivity methods and media that is known in the art, including, butnot limited to, communications over the Internet, wired, or wirelessnetworks using the appropriate protocols.

While this document contains many specifics, these should not beconstrued as limitations on the scope of an invention that is claimed orof what may be claimed, but rather as descriptions of features specificto particular embodiments. Certain features that are described in thisdocument in the context of separate embodiments can also be implementedin combination in a single embodiment. Conversely, various features thatare described in the context of a single embodiment can also beimplemented in multiple embodiments separately or in any suitablesub-combination. Moreover, although features may be described above asacting in certain combinations and even initially claimed as such, oneor more features from a claimed combination can in some cases be excisedfrom the combination, and the claimed combination may be directed to asub-combination or a variation of a sub-combination. Similarly, whileoperations are depicted in the drawings in a particular order, thisshould not be understood as requiring that such operations be performedin the particular order shown or in sequential order, or that allillustrated operations be performed, to achieve desirable results.

Only a few implementations and examples are described and otherimplementations, enhancements and variations can be made based on whatis described and illustrated in this disclosure.

What is claimed is:
 1. A method, comprising: receiving a first sensordata obtained from a first sensor that is located on a vehicle, whereinthe first sensor experiences rotation with respect to a first axisduring operation of the vehicle; receiving a measured value thatindicates a change in a height of at least a portion of the vehicleduring the operation of the vehicle; determining a degree of rotationexperienced by the first sensor based on the measured value; andobtaining calibrated sensor data that describes an area exterior to thevehicle by modifying the first sensor data based on the degree ofrotation.
 2. The method of claim 1, wherein the first sensor is locatedon a cab portion or a hood portion of the vehicle, and wherein therotation experienced by the first sensor is based on a pivot of the cabportion or the hood portion with respect to a chassis of the vehicle. 3.The method of claim 1, wherein the first sensor data includes image dataor light detection and ranging data.
 4. The method of claim 3, whereinthe first sensor data is modified by shifting the image data or thelight detection and ranging data using the degree of rotation.
 5. Themethod of claim 1, wherein the modifying the first sensor data comprisesidentifying a correction value associated with the degree of rotation,wherein an association between the correction value and the degree ofrotation is pre-determined.
 6. The method of claim 5, wherein thecorrection value includes a first symbol that is associated with aclockwise rotation of the first sensor with respect to the first axis,or wherein the correction value includes a second symbol that isassociated with a counter-clockwise rotation of the first sensor withrespect to the first axis.
 7. The method of claim 1, further comprising:receiving a second sensor data obtained from a second sensor that islocated on the vehicle, wherein the second sensor experiences rotationwith respect to a second axis during the operation of the vehicle; andaligning the second sensor data with the first sensor data thatdescribes the area that is exterior to the vehicle by modifying thesecond sensor data based on the measured value.
 8. A system, comprising:a computer comprising a processor and a memory storing instructionsthat, when executed by the processor, cause the computer to: receive afirst sensor data obtained from a first sensor that is located on avehicle, wherein the first sensor experiences rotation with respect to afirst axis during operation of the vehicle; receive a measured valuethat indicates a change in a height of at least a portion of the vehicleduring the operation of the vehicle; determine a degree of rotationexperienced by the first sensor based on the measured value; and obtaincalibrated sensor data that describes an area exterior to the vehicle bymodifying the first sensor data based on the degree of rotation.
 9. Thesystem of claim 8, wherein the first sensor is located on a cab portionor a hood portion of the vehicle, and wherein the rotation experiencedby the first sensor is based on a pivot of the cab portion or the hoodportion with respect to a chassis of the vehicle.
 10. The system ofclaim 8, wherein the first sensor data includes image data or lightdetection and ranging data.
 11. The system of claim 10, wherein thefirst sensor data is modified by shifting the image data or the lightdetection and ranging data using the degree of rotation.
 12. The systemof claim 8, wherein the modifying the first sensor data comprisesidentifying a correction value associated with the degree of rotation,wherein an association between the correction value and the degree ofrotation is pre-determined.
 13. The system of claim 12, wherein thecorrection value includes a first symbol that is associated with aclockwise rotation of the first sensor with respect to the first axis,or wherein the correction value includes a second symbol that isassociated with a counter-clockwise rotation of the first sensor withrespect to the first axis.
 14. The system of claim 8, wherein thecomputer is further caused to, when the instructions are executed by theprocessor: receive a second sensor data obtained from a second sensorthat is located on the vehicle, wherein the second sensor experiencesrotation with respect to a second axis during the operation of thevehicle; and align the second sensor data with the first sensor datathat describes the area that is exterior to the vehicle by modifying thesecond sensor data based on the measured value.
 15. A non-transitorycomputer readable storage medium having code stored thereon, the code,when executed by a processor, causing the processor to: receive a firstsensor data obtained from a first sensor that is located on a vehicle,wherein the first sensor experiences rotation with respect to a firstaxis during operation of the vehicle; receive a measured value thatindicates a change in a height of at least a portion of the vehicleduring the operation of the vehicle; determine a degree of rotationexperienced by the first sensor based on the measured value; and obtaincalibrated sensor data that describes an area exterior to the vehicle bymodifying the first sensor data based on the degree of rotation.
 16. Thenon-transitory computer readable storage medium of claim 15, wherein thefirst sensor is located on a cab portion or a hood portion of thevehicle, and wherein the rotation experienced by the first sensor isbased on a pivot of the cab portion or the hood portion with respect toa chassis of the vehicle.
 17. The non-transitory computer readablestorage medium of claim 15, wherein the first sensor data includes imagedata or light detection and ranging data, and wherein the first sensordata is modified by shifting the image data or the light detection andranging data using the degree of rotation.
 18. The non-transitorycomputer readable storage medium of claim 15, wherein the modifying thefirst sensor data comprises identifying a correction value associatedwith the degree of rotation, wherein an association between thecorrection value and the degree of rotation is pre-determined.
 19. Thenon-transitory computer readable storage medium of claim 18, wherein thecorrection value includes a first symbol that is associated with aclockwise rotation of the first sensor with respect to the first axis,or wherein the correction value includes a second symbol that isassociated with a counter-clockwise rotation of the first sensor withrespect to the first axis.
 20. The non-transitory computer readablestorage medium of claim 15, wherein the code further causes, whenexecuted by the processor, the processor to: receive a second sensordata obtained from a second sensor that is located on the vehicle,wherein the second sensor experiences rotation with respect to a secondaxis during the operation of the vehicle; and align the second sensordata with the first sensor data that describes the area that is exteriorto the vehicle by modifying the second sensor data based on the measuredvalue.